In the film packaging industry, packaging machines are used to form a pouch of a fusible film material which is filled with a bulk liquid or solid material. Subsequently, overlapping edges of the fusible films defining an open end through which filling occurs are heated between top and bottom sealing jaws to generate a continuous long seal.
A good seal is necessary to prevent any of the packaged material from leaking or falling out before it reaches the consumer and before it is ready for actual use. Another reason for ensuring good seals in film wrappers is that the wrapper is sometimes utilized as a protective cover and prevents elements outside of the package from reaching the material within. Defective seals depreciate the quality of the protection offered by the wrapper or may completely destroy the sanitary or other desired atmospheric conditions within the package.
Although good seals are readily appreciated within the industry, the actual time, temperature and pressure conditions under which a particular fusible film will seal is not readily appreciated by a packaging machine operator until a production packaging machine has been set to particular temperature and pressure conditions for actual production and seals are made. This may entail considerable set-up time and inspection of the seals to determine that reliable heat sealing is occurring and it may be necessary to re-set the machine during this set-up process if good heat seals are not being obtained.
It is accordingly one object of the present invention to provide a heat-sealing machine which simulates and monitors the actual temperature and pressure acting upon a fusible film through the top and bottom sealing jaws during the sealing cycle to provide a packaging machine operator with assurance that particular pressure and temperature operating parameters, at a selected simulated operating speed of a production packaging machine, will form high quality seals.
Another object of the invention is to allow for computer control of such a heat-sealing machine so that the operating parameters are easily programmable or re-programmable.
Another object is to provide a heat-sealing machine wherein at least one of the various operating parameters, and preferably all of the various operating parameters, can be continuously controlled during the sealing cycle and displayed either on computer screen or through hard copy.
Still another object is to provide assemblies and mechanisms as well as sensing and logic circuitry which may be embodied in production packaging or heat-sealing machines to monitor and self regulate selected temperature and pressure conditions during actual production.